Need help figuring out Itay-Switzerland-France trains

For Italy and France buy normal tickets, one ticket for each trip.
Italian Fares are so cheap if booked in advance (Trenitalia website) that a pass would be wasting money.
For your trip Interlaken (or wherever) to Paris, you again get very good advance purchase discounts.

Are you really staying in Interlaken? Most people recommend somewhere above Interlaken higher in the mountains (Grindelwald, Mürren, Wengen, Lauterbrunnen etc.).
A Swiss Pass, or a Berner Oberland Pass is probably worth it. You need to compare the pass costs with normal tickets for your planned trips. Depending which pass, it would cover all or part of your trip from the Italian and to the French border.
money.

Thank you Chris for your reply!

Actually we were looking for a place in Lauterbrunnen or Wengen at first, but found a good deal in Interlaken so we will stay there. And although Interlaken will be our base, we will be doing day trips to the places mentioned above.

Any idea about the Venice to Interlaken part? Do I buy separate tickets from Venice to (whatever border town there is) and then from there to Interlaken? or do they have a ticket straight from Venice to Interlaken? Thanks again for your great insight Chris!

From Venice to Interlaken, you can buy a ticket as far as Spiez at http://www.trenitalia.com/tcom-en
From Spiez it is just a short connecting train to Interlaken.

There are number of reasons that a Eurail is not a good value for you. I will excerpt from an answer I gave on another thread.

The Eurail pass only gives a 25% reduction between Interlaken Ost and the rest of the Berner Oberland, like Lauterbrunnen and the Jungfraujoch. That is why I suggest getting 30-day Swiss Half Fare Cards. You can also get a train specific advance purchase tickets for the TGV from Paris to Basel, which you get a discount. The other problem with the Eurail pass is that you will need to purchase seat reservations for the TGV train to Basel, about 10 EUR each or thereabouts for each passenger. They also limit the number of Eurail pass holders on the train, so you can still get shut out of the train you want if you do not make reservations soon enough. Italy, trains are less expensive, you might also find a "Bimbi Gratis" deal where kids ride free on the fast Freccia trains. Regional trains for short distances are very cheap and you can thank the taxpayers of Italy for that. In Italy, the Freccia trains require a 10 EUR seat reservation to be purchased for each passenger when using a Eurail pass. They are included when you buy tickets outright.

This person was going in the opposite direction, but my opinion holds. With the Swiss 30-day Half Fare Card, you can also get a free Family Card so you kids will ride with you for free. As I said, for Rome to Florence and Florence, the Bimbi Gratis deal holds and the kids ride free on the Freccia Trains when the parents buy full fare tickets. This deal is not available for Venice to Spiez, but you can probably get a "Smart" fare on the EC train when you buy advance purchase nonrefundable tickets. For Interlaken to Paris, take a Swiss train to Basel, using the Half Fare Card and the Family Card, then book tickets from Basel to Paris at https://en.voyages-sncf.com/en/tgv

For these advance purchase tickets, prices only go up, so the sooner you can commit and buy, the lower the price.

And for going to Paris, if Basel trains are booked you can also go from Interlaken via Geneva or Lausanne (I did via Lausanne because the available train was at lower fare.)

Oh wow! Thanks a lot Sam and Laura for great details and suggestions. Will book the tickets in a day or two. I really appreciate all the help I'm getting here. Can't thank enough!

When are you traveling? Tickets for dates only become available a certain amount of time ahead of time.

As always, the basic reference for all trains is www.seat61.com and he has lots to say about rail passes and why point-to-point tickets are often a better deal.

Thank you Kim and Southam!

We're going end of June and yes I did stumble upon seat61 and he sure has a lot of information. I've been going step by step and checking the deals too. I guess the Venice to Interlaken will be the only complicated (by that I mean changing 2-3 trains) journey. While looking at that leg of the journey I did see that there is just a 4 minute layover at Brig (between Milan to Brig and Brig to Spiez) Is that long enough to change trains? With four of us and luggage (although we don't plan on bringing those big heavy bags, iit's going to be a 15 day trip so there will be some luggage)

Once again thank you all for chiming in and giving confidence to this novice :)

As to the 4 minute change, it is from track 6 to track 7, directly across the platform. Your IC train will be waiting for you there. Be prepared by standing near the door with your luggage when the train stops. The station is shortly after the exit from the long Simplon Tunnel. So when it is dark for ten minutes or so, then it is suddenly daylight again, that's a hint that you should get up and grab your luggage and head to the door. Of course, they will also announce it on the PA system as well.

The Swiss do this all the time. They figure that 4 minutes is plenty of time for people to get off the train, walk the 20 feet or so across the platform and board the next train. So once that is accomplished, why hang around? People want to get to where they're going!

Thank you very much Sam for your easy to understand instructions! I am writing down all these instructions so that after I come back from the trip, some day I can help others like you all do.

I can't thank you all enough!

Sam mentioned the Swiss Half Fare card briefly in his first post, but you may not have realized the significance. It is the one card that will give the adults a full 50% discount on the very expensive Jungfrau trip. And the two kids will ride freevtherecand everywhere else is Switzerland if you request a free Family Cardvwith your Half Fare Cards.

You may need to activate the cards at your first stop in Switzerland (Brig?). This means seeing the agent to enter the start date and to verify the kids' birthdates on the Family Card. (Then you would catch the next train to Spiez, probably an hiur later). We had to show the kids' passports when we did this several years ago. Perhaps now they permit you to enter the data yourself, or have the trin conductor do it. Perhaps someone here knows the answer---or you could email customer service at SBB.

Thank you Lola! Looking to book all the tickets by tomorrow.

Thank you again!

Update-

I've booked all the trains for our journey within Italy (the "bimbi gratis" helped- thanks for that)

I've bought the Swiss half-fare card (along with the Family Card) Now the question is, I'm booking my journey from Venice to Interlaken. As suggested, I'm booking the Venice to Spiez (via Milan) thru Trenitalia and Spiez to Interlaken thru sbb.ch

When buying the latter trip, should I buy tickets for just me and my wife with half fare card (considering the kids travel free with the family card) or should I buy for all four of us? They do have supersaver tickets but doesn't show anything past May 24. Does anybody know how far ahead I can book those? We're planning June 25. Thanks!

Swiss tickets book ahead 30 days.

Thanks Sam!